Lot 10141 – 1937, Ophthalmological Congress in Cairo, 5m. in the issued colour red-brown, Royal imperforate sheetlet of nine plus gutter margin and an extra row of three

1937, Ophthalmological Congress in Cairo, 5m. in the issued colour red-brown, Royal imperforate sheetlet of nine plus gutter margin and an extra row of three, on watermarked paper, very fine and extremely rare; the only such sheetlet existing with the additional gutter row, unique.